The unused song from the NES version was ported to all of the Game Boy versions. Use the following Game Genie code to play the unused song at each version's title screen. Hugo has a slightly different version of the unused song.

Version

Code

Mickey Mouse

269-73D-D52

Mickey Mouse II

269-73D-D52

Bugs Bunny: Crazy Castle II

269-77D-D52

Hugo

261-94D-D52

Bugs Bunny Collection

364-B7D-F72

(Source: nensondubois)

Regional Differences

The game was first released in Japan as Mickey Mouse II. The United States saw Bugs Bunny: Crazy Castle II, which was later released in Europe as Mickey Mouse. Three years later, the game was rereleased in Europe as Hugo with a few noteworthy changes, including added Super Game Boy support and a slightly remixed soundtrack. Crazy Castle II was released in Japan as part of Bugs Bunny Collection, adding a few borders and the missing palettes that Hugo received.